The valhalla type-classes branch contains interesting new numeric types that want to be value classes.

See:
https://github.com/openjdk/valhalla/blob/type-classes/src/java.base/share/classes/java/lang/UnsignedInt.java#L35

Unfortunately, just adding the annotation is not enough, changes need also to be made to the makefile:

make/modules/java.base/gensrc/GensrcValueClasses.gmk

Which seems to contain an hard-wired list of all classes with the @MigratedValueClass annotation.

This seems suboptimal, and an opportunities for things to go off sync.